Method of making fiber containers



March 4, 1941. D. e. MAGILL 2,233,423

METHOD OF MAKING FIBE R CONTAINERS Filed Jan. 19, 1939 2 sheets-sheet 1 March 4, 1941. D. 3. M AGILL 2,233,423

METHOD OF MAKING FIBER CONTAINERS Filed Jan. 19, 1939 2 Sheets-Sheet 2 lYEZTOR. B

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ATTORNEYS Patented Mar. 4, 1941 PATENT OFFICE METHOD OF MAKING FIBER CONTAINERS Donald G. Magill, Great Neck, N. Y., assignor to American Can Company- New York, N. Y., a corporation of New Jersey Application January 19, 1939, Serial a... 251,802

5 Claims. (01. 93-94) The present invention relates to a method of making fiber containers or cans and has particular reference to improving the moisture-proof qualities of such cans by treatment of a wax-like coating.

In the manufacture of moisture-proof fiber cans films of asphalt have been applied between laminations of the paper board to produce the can and a coating of molten wax is sometimes applied to the outer and also to the inner surfaces of the cans to increase its moisture-resistance. Because of the technique of application of these materials according to present practices, moisture vapor resistance of such containers has been only nominal. As an example, it has been found in testing such containers in humid atmospheres that 50 grams of fused calcium chloride sealed on the inside of the can will become completely saturated with moisture within twenty-four hours, this showing conclusively that the can walls are not moisture-proof.

Extensive research has developed the present invention which is predicated upon the method step of suddenly chilling a molten wax or other wax-like film which has been previously deposited, while in molten condition, upon a greaseproof type of paper or paper stock such as parchment or glassine. This is done in a particular manner and an entirely different crystalline structure of the wax coating is obtained which increases the moisture resistance of the can film to as much as 50 percent or more over ordinary waxed cans. The impervious nature of the grease-proof paper on which the wax is deposited prevents soaking of the wax into the interstices of the paper or other fiber board used as the body of the can.

An object therefore of the invention is theprovision of a method of making moisture-proof fiber cans wherein a moisture-proof coating of molten crystalline wax is applied to the cans and immediately chilled and this is done in a manner to change the crystalline structure of the wax, producing a fiat crystalline structure. A normal needle-like crystalline structure is the result of the usual slower cooling. This improved crystalline structure increases the moisture resistance of the can to a large degree.

Another object is the provision of such a method wherein the chilling of the wax coating is effected by direct flushing of the wax with cold water or the like to bring about the desired change in crystalline structure of the wax.

Still another object is the provision of a method of chilling a wax-like coating when applied to a grease-proof non-absorbent part of the wall of a fiber can.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

Figure 1 is a top plan view of one form of apparatus for carrying out the method steps of the present invention, parts being broken away;

Fig. 2 is a side elevation of the cooling part of the apparatus the view being taken substantiall along a plane indicated by the line 2-2 in Fig. 1, parts being broken away; and

Fig. 3 is a transverse sectional view of the cooling step as taken substantially along the line 3-3 in Fig. 1.

In the present embodiment of the invention there is disclosed the steps of forming a tubular structure on a mandrel by the spiral winding process. Two or more plies of heavy chipboard are formed in the spiral winder in the customary manner to provide a fiber tube.

Parchmentized paper, glassine or other impervious type of sheet fiber stock is then introduced into the tubular structure being wound on the winder, the inner face of this parchmentiz'ed element being coated with molten asphalt or similar materials which are preferably moisture-proof as well as adhesive. This coating step is best done just as the parchmentized paper enters the tubular structure of the body wall.

The other side of the parchentized paper is preferably coated with higher melting point waxes such as parafl'in wax of a nature to insure an outermoisture-proof coating for the formed tubular structure.

This wax-like surface of the parchmentized paper while still in its molten condition is then suddenly chilled by passage beneath a film of cooling medium such as cold water which produces a fiat crystalline structure in the wax. A can made with such a treatment is much more moistureproof than it would be were the same wax allowed to cool in the regular manner. The broad, crystalline formation of the wax reduces the number of crystals and from a mere mechanical standpoint, the fiat faces of the larger crystals thus formed, provide a better protecting surface for the resulting can.

As a preferred embodiment of the present invention a long fiber tube A (Fig. 1), from which can bodies of a desired length may be cut off. is

v the opposite side of the machine and at an angle wound in the conventional spiral manner. This preferably includes winding of two strips of fiber board B and C which produces a multiple ply or multiple layer tube, this being a well known construction. Winding of the two strips is done simultaneously on a mandrel as indicated in the drawings, the strip C being coated with a suitable adhesive E for binding the inner plies firmly together.

A third strip F of thin glassine or parchmentized paper is spirally wound around the tube formed by the union of the other two strips B and C. This strip F is coated on its inner surface with asphalt or other moisture-proofing, adhesive material G which acts as a further moisture-proof agent for the tube, the asphalt being interposed between the outer layer of the fiber tube and the glassine strip F.

The outer surface of the strip F is preferably coated with a wax-like material H such as paraffin wax or other crystalline wax. Such a wax provides the outer moisture-resistant coating for the finished can which is made from the tubular structure including the composite strips B, C and F. Owing to the nature of the strip F neither the asphalt G nor the wax H soaks into the parchmentized strip but remains as a coating film. This feature in itself is important.

Immediately after the strip F is wound onto the tube A the molten wax is chilled by flushing it with a cooling medium preferably a stream of cold running water J or thelike (Fig. 3). It is this stream of water which changes the crystalline structure of the outer surface wax and thereby greatly increases its moisture resistant properties. Tube A, made up of these various parts, provides the structure from which moisture-proof can bodies may be obtained merely by cutting off to any desired length in the usual manner.

One form of apparatus as illustrated in the drawings for carrying out the method steps of the mandrel H which is supported in a clamp block I 2 formed on a machine main frame l3. The tube A is wound into spiral form on this mandrel. The strip of fibre B is fed onto the mandrel at an angle thereto in any suitable manner and is guided into position by guide blocks M which are secured to the frame l3.

The fiber strip C is fed onto the mandrel from thereto as illustrated in Fig. 1. This strip is also wound in spiral fashion over the top of the already spirally wound strip B, the strip C being guided into position by a guide bracket I8 which is secured to the main frame l3. As it passes onto the mandrel, the inner surface of the strip C (the top as viewed in Fig. 1) is coated with the adhesive E by an applying roller i9. Such a roller receives its supply of adhesive from a suitable source not illustrated in the drawings.

Winding of the two fiber strips B, C to produce the tube A is efiected by an endless belt 2| which is obliquely wrapped around the mandrel as shown in Fig. 1 and which takes over spaced pulleys 22, 23. These pulleys are disposed at an angle to the mandrel and are driven in unison in any suitable manner, such as by gearing connected and rotated by drive shaft 25. The pulleys and the drive shaft are suitably carried in a belt bracket 26 which is bolted to the main frame l3.

The drive shaft 25 is preferably rotated through proper gearing. not shown, by a main instant invention includes. a stationary drive shaft 2'! which is journaled at one end in a bearing 28 formed in the belt bracket 26 and at its opposite end in a bearing 29 formed in abracket 3| secured to the main frame. Adjacent the bracket 3| the shaft carries a driving pulley 32 which may be connected by a belt to a suit- V able source of power. The oblique arrangement of the belt 2! rotates the tube A in a spiral fashion and thereby advances the tube along the mandrel. The belt also exerts considerable pressure upon the wound strips so that they are formed into a compact body wall bonded together by the adhesive E.

The strip F of glassine or parchment is also fed onto the tube A at an angle as shown in Fig. 1 and in any suitable manner. The asphalt G is applied by a roller 35 which may receive its asphalt from any suitable source of supply.

The molten wax H is preferably a paraffin wax of a melting point of 133 to degrees F. It may be applied to the strip by a roller 36 which is mounted in a reservoir 31 where it rotates in a bath of the wax contained in the reservoir. The reservoir may be suitably piped for circulation of a heating, medium in order to keep the wax in liquid form while in the reservoir.

Chilling of the molten wax to change its crystalline structure is preferably accomplished by means of a flushing element or spray head 4| (see also Figs. 2 and 3) which is connected by an 1 inlet pipe 42 to a suitable source of supply of a cooling medium, such as cold water, brine or the like. This spray head incloses a flush chamber just before the point of discharge and insures a gentler discharging action of the cooling medium.

Where cold 'Water is used as the cooling medium the temperature of this water should be approximately 55 degrees F. for best results.

The water strikes the wax-like surface with a very soft impact so as not to disturb the surface as it undergoes its natural crystalline change. Where this is done gently no ripples or other irregularities will result. An improved glassy appearance also follows from this treatment. A valve 43 is provided in the pipe line for convenience in shutting off or turning on the Water and for regulating its force of discharge.

The spray head II is located directly over the tube A on the mandrel H and to one side and is provided-with an elongated outlet opening 44 in the bottom thereof which extends the full length of the head. The falling water running off along one side of the revolving tube is caught in a It is thought that. the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the steps of the process described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the process hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A method of making fiber containers, which comprises producing a fiber tube, winding on said tube a strip of paper carrying a coating of molten wax, said wax coating being on the outer surface of the wound paper, and suddenly chilling said molten wax coating so as to change its crystalline structure thereby greatly increasing its resistance to moisture.

2. A method of making fiber containers which comprises producing a fiber tube, winding on said tube a strip of moisture resistant paper carrying a coating of molten wax on one surface and a coating of molten asphalt on the other surface, and suddenly chilling said molten wax coating so as to change its crystalline structure thereby greatly increasing its resistance to moisture.

3. A method of making fiber containers, which comprises winding a fiber strip into a spiral tube,

applying a coating of adhesive to a second strip of fiber, winding said second strip in spiral fashion over said first strip thus producing a tube of fiber layers bonded together. by said adhesive, winding onto said tube a strip of thin moisture resistant paper carrying a molten wax coating on its outer surface, and suddenly chilling said molten wax coating so as to change its crystalline structure thereby greatly increasing its resistance to moisture.

4. A method of making fiber containers, which comprises winding a fiber strip into a spiral tube, applying a coating of adhesive to a second strip of fiber, winding said second strip in spiral fashion over said first strip thus producing a tube of multiple layers bonded together by said adhesive, winding onto said tube a strip of thin moisture resistant paper carrying a molten wax coating on its outer surface and also carrying a coating of asphalt on its inner surface, said asphalt binding said' strip to said tube and also serving as a moisture-resistant for the tube, and suddenly chilling said molten wax coating so as to change its crystalline structure thereby greatly increasing its resistance to moisture.

5. A method of making moisture-proof fiber containers, which comprises passing a strip of paper onto a forming mandrel, feeding another ,strip of paper coated with adhesive upon the mandrel and over said first mentioned strip and rotating and advancing the resulting tubing upon the mandrel, the outer of said other strip carrying a coating of molten crystalline wax on its outer surface, and suddenly chilling said molten wax coating on the outside of the tube so as to change the crystalline structure of the wax thereby greatly increasing its resistance to moisture.

DONALD G. MAGlLL. 

